Structural analysis of graphene synthesized by chemical vapor deposition on copper foil using nematic liquid crystal texture

Several studies have focused on synthesizing large-size graphene with an uniform crystal structure. However, graphene synthesized thus far is generally grainy. Grain properties such as size, shape, and crystal orientation are the basis for improving quality. In this study, a nematic liquid crystal is used to observe the several structural properties of graphene synthesized by chemical vapor deposition on the copper foil at once. The liquid crystal texture indicates the grain boundaries, and the liquid crystal directors reveal the crystal orientations of the graphene. The graphene islands appear to have plural grains of different crystal orientations, and the orientation of every lobe in island is mapped. The crystal rotating angles between layers in multilayer graphene are determined. In addition, the fine repeating lines on the graphene are shown to consist of graphene wrinkles. The liquid crystal does not damage graphene, and the process is easy, fast, reliable and applicable to large size; thus, the liquid crystal can be widely applied to analyze the structure of large-size graphene. (C) 2014 Elsevier Ltd. All rights reserved.